JPS59109507A - Production of modified saturated polyester resin composition - Google Patents

Abstract

PURPOSE:To form the titled resin composition with its heat resistance improved without detriment to its transparency, by mixing a saturated polyester resin with an alkyl group-containing compound, and irradiating the mixture with an ionizing radiation. CONSTITUTION:100pts.wt. saturated polyester resin (e.g., polyethylene terephthalate) is melt-blended with about 0.5-10pts.wt. alkyl group-containing compound (e.g., trialkyl isocyanate). The obtained composition is thermally formed, if necessary, and irradiated with an ionizing radiation (e.g., beta-rays, gamma-rays, or accelerated electron beams) at room temperature (absorption does of about 1-60 Mrad) to crosslink the polymer chains with the alkyl group-containing compound. In this way, a modified saturated polyester resin composition is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing a modified saturated polyester resin composition. More specifically, the present invention relates to an efficient method for producing a modified saturated polyester resin composition that has improved heat resistance and does not impair transparency.

Generally, saturated polyester resins, particularly polyethylene terephthalate (hereinafter abbreviated as PFiT), are widely used as fibers, films, and various molded products due to their excellent physical and chemical properties. In particular, molded containers made of PET have recently attracted attention because they have excellent properties such as mechanical strength, gas barrier properties, and transparency.

However, although molded products using PET have the above-mentioned characteristics, their heat resistance is still insufficient, and improvement thereof has been desired for a long time.

Methods to improve the heat resistance of polyester include keeping the temperature of the mold at a high temperature during molding, and adding compounds that promote the crystallization of saturated polyester (for example, benzoic acid, terephthalic acid, stearic acid, phosphonic acid). , or an alkali metal salt of phosphinic acid). However, the former method requires a long contact time with the mold, making it difficult to say that it is an industrially economical method for manufacturing molded products, and the latter method causes whitening of the preform, making stretch blow molding difficult. However, there were drawbacks such as the molded product having an opaque appearance.

This invention was made in view of such conventional problems. The inventors of the present invention have conducted intensive studies to find a saturated polyester resin with good heat resistance that does not have the above-mentioned drawbacks.
By incorporating a small amount of an allyl group-containing compound into the saturated polyester resin to be molded and irradiating the resulting molded product with KM radiation, a saturated polyester resin molded product with improved heat resistance and good transparency can be produced efficiently. We discovered this fact and arrived at this invention.

Some of the allyl group-containing compounds used in this invention are conventionally known as vinyl monomers for curing thermosetting unsaturated polynisder resins; Its use is not known at all, and even if it is simply added to a saturated polyester resin and a heat curing treatment is attempted, the desired molded product cannot be obtained. Additionally, technology for modifying plastics with ionizing radiation is also known for polyethylene, etc., but depending on the type of plastic, molecular chains may collapse or become disproportional, and good crosslinking may not be achieved uniformly. Therefore, it cannot necessarily be said to be an effective means of reforming. Furthermore, even if a saturated polyester resin (molded article) is simply irradiated with ionizing radiation, good crosslinking will not occur and the desired molded article will not be obtained.

In other words, the most distinctive feature of this invention is the combination of irradiation with ionizing radiation and a specific compound. The point is that it has made it possible to modify the

Thus, the present invention provides a method for producing a modified saturated polyester resin composition, which comprises mixing a saturated polyester resin with a small amount of an allyl group-containing compound and irradiating this composition with ionizing radiation. .

In this invention, the saturated polyester resin refers to a thermoplastic saturated polyester resin that does not have unsaturated bonds involved in curing in the molecule, which is obtained by a polycondensation reaction between a polybasic acid and a polyhydric alcohol. do. Specific examples of these include PIIT, PBT
(polybutylene terephthalate), poly 1,4-cyclohexylene dimethylene terephthalate, polyethylene terephthalate/isophthalate copolymer, poly 1.
Examples include 4-cyclohexylene dimethylene terephthalate/isophthalate copolymer, and various additives may be included.

Examples of the allyl group-containing compound used in this invention include compounds having at least one active allyl group, such as triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, diallyl phthalate, and diallyl chlorendate. , triallyl 1.2.4-
Examples include benzene tricarboxylate, diallyl hexahydrophthalate, diethylene diallyl ether, allyl glycidyl ether, allyl methacrylate, and among these, those containing three allyl groups are preferred.
Triallylisocyanurate is most preferred.

A small amount of allyl group-containing compound is mixed into the saturated polyester resin. The mixing at this time is usually carried out by melt mixing, and it is convenient to mix using an extruder and form pellets or granules, but it is also possible to form the desired shape by mixing using a mold. In this case, the small amount of the allyl group-containing compound mixed with the saturated polyester resin is 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, per 100 mm parts of the saturated polyester resin. . 0.1
If the amount is less than 2 parts by weight, the effect of addition is insufficient;
If the amount is more than 0 parts by weight, the moldability of the resulting composition will deteriorate, which is not preferable.

The composition thus obtained is irradiated with W and releasing radiation after it is directly or optionally subjected to thermoforming.

Normally, it is preferable that the above-mentioned composition be molded into the shape of a final product (for example, a container) using a mold, etc., which does not require any subsequent molding processing, and then irradiated.

Examples of m-separated radiation used in this invention include β-rays, r-rays, accelerated electron beams, and radiation obtained by reflection and scattering of these radiations, and radiation sources include nuclear reactors, radioactive isotopes, and electron beams. Examples include accelerators and the like.

Irradiation is performed at room temperature, and the irradiation atmosphere is air or an inert gas (nitrogen or argon gas). The m-view required for modification varies depending on the shape and thickness of the irradiated object, but
This is usually done so that the absorption line is 1 to 60 Mrad, preferably 10 to 60 Mr;+d. 60 Mrad
Exceeding this is not preferable since there is a risk of polymer chain fragmentation.

The modified saturated polyester resin composition of the present invention thus obtained has polymer chains crosslinked via the allyl compound due to the cooperative action of the m-separating radiation and the allyl compound, and has a high gel fraction. It has improved heat resistance. Furthermore, since it does not contain compounds that promote crystallization like conventional products, there is no loss in transparency, and the appearance is comparable to that of regular PE'l'' molded products. .

As shown from the above explanation, according to the production method of the present invention, the addition of a specific compound and a short time (usually within 10 minutes)
By irradiating the saturated polyester resin composition with separable radiation (which eliminates the need for heat treatment or sensitizers such as radical generators), the saturated polyester resin composition with good heat resistance can be produced efficiently. It is industrially useful.

Hereinafter, the present invention will be explained in detail by showing examples, but the present invention is not limited thereto.

Examples IO FN parts of the various additives shown in Table 1 were weighed against 100 parts by weight of polyethylene terephthalate having an average molecular weight J of 1.6000, and mixed in a blender. Then it was put into an extruder and melted WfI! The mixture was mixed, rapidly cooled, and then pelletized.

The obtained pellets were irradiated with a tr beam (tr) using a 750 KV, 40 mA transformer-type electron beam accelerator.

Table 14 shows the gel fraction measurement results of irradiated pellets and comparative examples.
This is shown.

Table 1 Gel fraction is the ratio of undissolved residue to sample resin weight when irradiated pellets are heated and dissolved in 0-chlorophenol at about 120°C.

As is clear from Table 1, the composition irradiated with an electron beam does not completely dissolve in 0-chlorophenol, which is known as the best solvent for polyester, and significantly more than 50% remains as insoluble matter. Has chemical resistance.

The resulting chart is shown in FIG. 1 together with a comparative example (obtained with 20 Mrad irradiation) (the solid line indicates the comparative example, and the broken line indicates the example).

In the comparative samples, all polyester glass transitions,
Peaks associated with crystallization and melting appear, but when the gel fraction is 20
% or more, as shown by the broken line in FIG. 1, the peaks associated with glass transition and crystallization disappear, indicating improvement in heat resistance.

Regarding transparency, non-irradiated Ryomachi molding and I+? There was no change in appearance between , and the irradiated object.

[Brief explanation of the drawing]

FIG. 1 is a differential thermal analysis curve illustrating the thermal properties of a modified saturated ester resin composition obtained by the production method of the present invention.

Claims (1)

[Claims] (1) A method for producing a modified saturated polyester resin composition, which comprises mixing a small amount of an allyl group-containing compound with a saturated polyester resin, and irradiating this composition with ionizing radiation.